This invention relates, in general, to semiconductor devices and, including, but not limited to, a vertical cavity surface emitting laser (VCSEL) integrated with a heterojunction bipolar transistor (HBT).
There is a need to integrate electronic components with optical devices to provide for optoelectronic integrated circuits (OEICs). It would be desirable to integrate electronic components with lasers, in particular VCSELs. A problem encountered with integrating VCSELs with electronic components is that the highly non-planar structure of VCSELs makes it difficult to integrate electronic devices with them. The conventional integration approach is to provide a set of layers dedicated for the VCSEL on top of another set of layers dedicated for the electronic component on a single substrate. This approach forms a structure which exacerbates the problem of non-planarity of VCSELs.
Planar structures are desirable from a process and packaging point of view. Devices with high aspect ratio features make contact from the top of the device to the plateau of the device a very difficult processing problem. In addition, fine line lithography, which is necessary for high performance devices, is difficult to use in highly non-planar structures.
Thus, there exists a need to provide a means of integrating VCSELs with electronic components to make possible high performance, monolithic OEICs. A planar structure would facilitate the fabrication of these high performance circuits.